Adhesive products have been designed which are created specifically to enhance their ability to be removed from a substrate after being adhered to such substrate without substantially damaging the substrate surface or leaving substantial adhesive residue thereon. Products include items such as paper notes having a layer of easily removable adhesive adhered to one surface, such as the Post-it.TM. Note products available from Minnesota Mining and Manufacturing Company of Saint Paul, Minn. It is also known to provide double-sided adhesive products including similar easily-removable adhesive.
Another type of product which has been recently developed is a single-sided or double-sided adhesive tape having conventional pressure-sensitive adhesive on one or both major surfaces thereof, and which includes a tape backing comprising a highly extensible material. See for example European Patent Application 92.903259.7.
These tapes operate in that when the backing is stretched after the tape is adhered on one side or both sides, the adhesive stretches and undergoes clean interfacial debonding from the substrate or substrates to which it is adhered. Such removal typically progresses from one end of the tape to the other as the tape backing is stretched at an angle preferably no greater than about 35.degree. from the surface of the substrate. That is, as the tape is stretched from one end, it debonds from the end being stretched toward its distal end.
The adhesive tapes described in the aforementioned European Patent Application 92.903259.7 include plastic backings. That means, as the backing is stretched, it is permanently deformed and has relatively low elastic recovery. Tapes described include single-sided tapes, double-sided tapes, and tapes comprising film layers, foam layers, and laminates of films and/or foams. In double-sided adhesive tape constructions, both adhesive surfaces debond at the same time and progress substantially at the same rate from the stretched end toward the distal end as the tape backing is stretched.
Co-pending U.S. patent application Ser. No. 08/308,937, which is commonly owned by the Assignee of the present invention, discloses a number of stretchable release tapes comprising constructions of films, foams, and laminates of films and/or foams. Again, such tapes include conventional pressure-sensitive adhesives.
Another type of stretchable release adhesive tape is described in U.S. Pat. No. 5,409,189 to Luhmann, wherein the adhesive tape backings utilized comprise elastic materials. Elastic, as opposed to plastic materials described above, means materials that are stretchable without substantial plastic deformation and which have high elastic recovery after stretching and release. Like the plastic tapes described above, elastic tapes can be single-sided or double-sided and the stretching of the backing causes adhesive stretching and subsequent debonding of the adhesive surface or surfaces from the stretched end to the distal end as the tape is stretched.
Double-sided adhesive tapes are particularly useful in joining and mounting applications. Stretchable release double-sided tapes provide secure bonding to both surfaces with clean removal from both surfaces without substantial damage or adhesive residue. A problem is that such double-sided adhesive tapes simultaneously debond from both adhered sides as the tape is stretched for removal. In applications where these tapes are used to adhere an object to a wall or other surface, the release from both the object and the other surface at the same time may cause the adhesive tape to snap back in the direction of the stretching, similar to the snapping effect of a stretched rubber band, or may cause the object to be catapulted, particularly if the object is not held while being removed. This snap-back of the tape occurs at the point of adhesive release when the resisting force of adhesion to the wall suddenly drops to zero, This effect is exacerbated by the elasticity or recovery properties of the tape.
The above described stretchable tapes are known to be applicable for many applications including the mounting of objects, such as hooks or other hanging devices, to walls, etc.; joining or assembly applications; cushioning or sound-deadening applications; closure applications, such as container closures, e.g. closures for boxes, food and beverage containers; and removable labels.